Re: No exceptions?

>> paul c wrote:
>>
>>> Jon Heggland wrote:
>>>
>>>> paul c wrote:
>>>>
>>>>> Let me re-phrase my original question: Is there a logical flaw in
>>>>> substituting TABLE_DUM for x in the expression "x join y" when x is
>>>>> not
>>>>> in the catalogue?
>>>>>
>>>>
>>>> I don't know what precisely you mean by "logical flaw", so I'll pass
>>>> judgement. If something should be substituted for x (a "default value",
>>>> so to speak), TABLE_DUM does seem the natural choice, though, as it
>>>> corresponds to false/zero in some sense.
>>>> ...
>>
>> I suppose my "logic", if I may call it that, went like this (at
>> evaluation time):
>>
>> 1) according to syntax, x must be a relation

>> 4) since x has no attributes and no tuple, it must have the same value
>> as TABLE_DUM

> > Or it could be an expression that evaluates to a whole set of values.> ...

Another guess, are you basically saying that as far as you're concerned,
x could stand for anything and everything? If you are, then I guess
there is a deep flaw in my assumption that I could stipulate via syntax
that x is required to be a relation.